Numerous embodiments of regulating mechanisms for exterior rear view mirrors of motor vehicles are known of the type described earlier. The base member secured to the mirror mounting and the cover to be coupled to the base member of said mechanisms are described below. In general, the base member has a generally spherical segment shape with a closed smaller base and with an open larger base adapted for receiving the cover as if it were a knuckle, the smaller base of the base member and the cover having respective and complementary positioning means of the cover with respect to the base and thus positioning the mirror mounting plate and the mirror glass as regards the mounting. Furthermore, the base member and the cover are provided with vibration dampening means, which essentially consist of the elastic deformation of the base member about the cover, the main purpose of which is to absorb the vibrations caused by the vehicle when in motion being transmitted to the mirror mounting plate, vibrations which affect the stability of the image given by the mirror assembled onto the same and, as a consequence, making the driving of the motor vehicle difficult.
A known form of embodiment of positioning means of the cover guided by means of a mechanical control device through cables, is described below. The smaller base of the base member is fitted with an outwardly directed perpendicular centred protuberance and has securing means at the ends of the steel cable sheath of the control cables, whereas the cover is fitted with a central portion provided with securing means of the ends of the steel cable ends. In addition, the centred protuberance of the base member and the central portion of the cover are provided with respective and complementary support means, adapted in such a way that when the user acts on the control device, it is transmitted through the control cables to the cover, which, by pivoting over the support means then occupies the desired position.
In the known embodiments of regulating mechanisms the positioning means and dampening means are arranged on the base member and on the cover, which presents the drawbacks described below. For a specific base member and cover the dampening means operate in suitable conditions up to specific dimensions of the mirror mounting plate secured to the cover, but from which the dampening means do not succeed in sufficiently absorbing the vibrations transmitted to the mirror mounting plate because of the vehicle's motion, even when the vehicle is stationary, and occurs under certain inoperative conditions; as a consequence of the previous drawback, several models of base member and cover suited to the mirror mounting assembly dimensions are needed, leading to a costly regulating mechanism.